Re: [Xen-devel] [PATCH] Fix restore handling checks

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 21/06/2010 17:30, "Michal Novotny" <minovotn@xxxxxxxxxx> wrote:

> Hi,
> this is the patch to fix restore handling to implement some more checks
> to support more checks than for UUID and name duplicity. This patch
> basically disallows the migration/restore of IDE drives with the
> read-only flag since this is not supported according to the ATAPI/IDE
> specifications so we should disallow this for both domain creation and
> domain migration/restore.

What about CD-ROMs? This would break my test domain config, for example.

> This patch implements it for both create and
> restore/migrate functionality.
> 
> Also, the check whether the host machine does have enough memory
> available for the guest has been implemented which can be the real issue
> when you try to migrate a guest from one machine to another that is not
> having enough memory for this guest. The guest memory gets transferred
> but it fails to run so it's not running on either of those machines
> (i.e. domain is not on the destination nor source host machine).

Failed restore should get reported back to the host that is saving the guest
state, and cause that machine to resume execution of the original VM. Does
that not work for you?

Possibly checking up front for available memory on the target is a good
idea, but it shouldn't be *essential* if the error handling is up to par.

 -- Keir

> I did try it with restore functionality now since I've been able to make
> it working for save once so I'm currently using one save image for the
> testing but unfortunately I'm having many issues with the common
> migration and save functionality since I've been able to make it working
> once to save it correctly. Fortunately the restores for this one
> particular save image is working fine. I was also thinking about 2
> concurrent migrations to the guest and/or save with the concurrent
> migration and it should be the issue (although it's not been tested
> because of reasons described above) since the domain gets created and
> it's available in the XendDomain list (i.e. xc.domain_getinfo() list) so
> it shouldn't be an issue here.
> 
> Michal
> 
> Signed-off-by: Michal Novotny <minovotn@xxxxxxxxxx>



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